As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLIMBING THROUGH FL19.5 RECEIVED CABIN ALTITUDE CAUTION. INITIATED DESCENT AND RECEIVED CABIN ALT WARNING, LITTLE TO NO AIRFLOW FELT IN COCKPIT, C/W QRH IN ITS ENTIRETY. ***AIRCRAFT REMOVED FROM SERVICE*** RE-SECURED LINE TO WATER SEPERATOR REF AMM SUP 15-132A, LEAK CHECK GOOD WITH UNPRESSURIZED A/C USING APU.